For the purpose of this invention a rolling shutter is a structure which comprises a plurality of bar-like members or slats which are laterally articulated to one another or contiguously interconnected so that the assembly can be rolled up, coiled or wound upon a drum, mandrel or shaft, usually disposed above a lintel in a door structure. Such rolling shutters are used to close the fronts of stores and other business establishments as security devices; they may be used as garage doors or as warehouse or trucking-port doors, as partitions to subdivide large spaces and wherever a structural opening requires reinforcement or closure and wherever subdivision of a space is desired.
It has been proposed heretofore to provide the bars or slats in the form of extruded synthetic-resin hollow profiles, i.e. prismatic tubular structures in which an elongated compartment is laterally closed for stiffening purposes. On opposite lateral edges the bar can be formed with a groove or mortise into which a tongue or tenon of the other edge of another bar can be fitted to form an articulation enabling each slat to rotate relative to the adjacent or laterally contiguous slat. The interfitting formations on the opposite lateral edges of the slats can lock together to form a rigid curtain or wall structure or can be loose so as to freely rotate at least limitedly relative to one another. The tongue member can be bent and formed on its free end with a flange which is received in a recess in the grooved portion of an adjoining bar. The grooved portion itself can be formed with an arcuate seat against which the tongue can rest to enable one slat to roll on the next within their common joint.
The synthetic-resin profile can be continuously extruded and cut to the desired length and hence can be manufactured relatively inexpensively.
In the German utility model (Gebrauchsmuster) 1,984,759, the flange-engaging surface and arcuate formation of the groove forms a transverse wall which lies substantially horizontally in a lowered condition of the curtain and, with the connecting member of the next lower slat, is closed. This arrangement is not statically as secure as desired, resulting in an assembly which is not always structurally satisfactory.